Need Help with log Equation

So in my university Astronomy course I need to use log equations, I have never done any before and do not know what log is, although I am expected to...the equation I need to solve is m - M = 5 x log(d/10) ...d is 1.34 for the specific question...I don't understand what I am supposed to be solving for (is it either the m or the M??) and I don't know what that 5 is doing there (I have no breakdown of what each part of the equation means). Please explain what log is and how to solve the equation, thank you!

I understood what you meant by not enough information; meaning there is no way to isolate one variable. That's why I wasn't sure if I was understanding correctly or not because there was no explanation about log there was just the equation at the top of the page and then that question...I'll have to speak to my professor about it and get him to explain. Thanks again!